Radiation-induced bystander effects (RIBE) wasdemonstrated with accumulated evidence. Recently,several studies have focused on the role of DNAdamage and repair in the bystander response, but the heavy ions induced, especially cell cycle-correlative RIBE are still largely unclear. Our present study found that G2/M phase cells had the largest contribution to the RIBE induced by carbon ions irradiation and identified a pivotal role for DNA-PKcs and ATM in this process as two independent factors.